Abstract : Operating and control characteristics of several combustion chambers for solid fuels were studied experimentally. It was possible to maintain a uniform exit-gas temperature of 1150 C over a period of several hours in a self-feeding unit fired with green wood or charcoal. This permits heat flux consistent with usual practice in design of thermoelectric generators, at about 4.5 thermal watts/sq. cm., with moderate pressure drop for heat transfer. Design studies of a Stirling-cycle air engine are in progress, and thermoelectric properties of several combinations of semiconductive thermoelectric materials were studied. Research on these studies will continue, followed by studies of vapor-cycle engines and metallic-thermocouple systems. (Author)